本试验旨在研究天蚕素A-马盖宁杂合肽对小鼠小肠黏膜结构、黏膜免疫功能和肠道菌群的影响。选取18只健康且体重相近的 BALB/c 小鼠随机分成3组：对照组（生理盐水0．75 mL/d灌胃）、低剂量杂合肽组（0．26 mg/mL的杂合肽0．75 mL/d灌胃）、高剂量杂合肽组（0．52 mg/mL的杂合肽0．75 mL/d灌胃）。试验期为6周。结果表明：1）2个杂合肽组十二指肠绒毛长度均显著大于对照组（ P＜0．05），各段小肠的隐窝深度均显著低于对照组（ P＜0．05），各段小肠绒毛长度/隐窝深度均显著高于对照组（ P＜0．05）。2）与对照组相比，2个杂合肽组各段小肠黏膜内免疫球蛋白A阳性表达水平均显著升高（P＜0．05）。3）2个杂合肽组小肠黏膜内白细胞介素（IL）-2、干扰素-γ（IFN-γ）及IL-4含量均显著高于对照组（P＜0．05），而IFN-γ/IL-4各组之间差异不显著（ P＞0．05）。4）2个杂合肽组盲肠内容物中的大肠杆菌数量均显著低于对照组（P＜0．05），双歧杆菌与乳酸杆菌数量均显著高于对照组（P＜0．05）。由此得出，天蚕素A-马盖宁杂合肽灌胃能改善机体小肠黏膜结构；可促进免疫球蛋白A的表达来提高小肠黏膜免疫防御功能；可促进IL-2及IFN-γ的分泌来提高肠道细胞免疫水平，促进IL-4的分泌以提高肠道体液免疫水平并能够保持辅助性T细胞（ Th）1/Th2的平衡状态；可有效降低肠道致病菌大肠杆菌的数量并显著增加肠道益生菌双歧杆菌和乳酸杆菌的数量。%This experiment was to study the effects of cecropin A-magainin hybrid peptide on small intestinal mucosal structure, mucosal immune function and intestinal microflora in mice. The eighteen healthy BALB/c mice with similar weight were randomly divided into three groups: control group ( given 0.75 mL saline water by gastric lavage) , low dose of hybrid peptide group ( given 0.75 mL 0.26 mg/mL cecA-mag peptide by gas-tric lavage) , and high dose of hybrid peptide group ( given 0.75 mL 0.52 mg/mL cecA-mag peptide by gastric lavage). The feeding experiment lasted for 6 weeks. The results showed as follows: 1) the villous length of duodenum in two cecA-mag peptide groups was higher than that in control group ( P<0.05);the crypt depth of every part of small intestinal in two cecA-mag peptide groups was significantly lower than that in control group (P<0.05); and villous length/crypt depth (V/C) of every part of small intestinal was significantly higher than that in control group ( P<0.05) . 2) Compared with control group, the positive expression levels of IgA in duodenum, jejunum, and ileum were significantly higher in two cecA-mag peptide groups ( P<0.05) . 3) The contents of IL-2, IFN-γ and IL-4 in two cecA-mag peptide groups were significantly higher than those in con-trol group (P<0.05). IFN-γ/IL-4 was not significantly different among different groups (P>0.05). 4) The number of Escherichia coli in two cecA-mag peptide groups was significantly lower than that in control group ( P<0.05) , the number of Bifidobacterium and Lactobacillus in two cecA-mag peptide groups was significantly higher than that in control group (P<0.05). It is concluded that cecropin A-magainin hybrid peptide can im-prove mucosal structure of small intestine and may enhance intestinal mucosal immune function through enhan-cing the expression of IgA, improve cellular immunity through enhancing the secreting of IL-2 and IFN-γ, im-prove humoral immunity through enhancing the secreting of IL-4, keep the balance of Th1/Th2, effectsively decrease the number of Escherichia coli of pathogenic bacteria and increase the number of Bifidobacterium and Lactobacillus of intestinal probiotics.
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